Sir Philip Green (pictured), Kate's close friend and owner of the high street chain, said: "It has been fantastic for us and fantastic for her, but [the designs] take more and more time and she cannot do this full-time anymore."

Speaking about the collaboration to The New York Times online blog recently, Kate said: "When we started the project we didn't have an end in mind but I'm really proud of all 14 collections.

"I've learned a lot about the design and development process; experiences that I'd only ever seen informally through being a model."